1. Field
Embodiments of the present invention generally relate to methods for etching a substrate.
2. Description of the Related Art
Some etch reactors employ a cyclical etch process that includes several recipe steps, such as etch and deposition, or etch, flash, and deposition. The cyclical etch process may use a time multiplexed gas modulation (“TMGM”) system or a Bosch system to sequentially provide etchants and deposition species. The deposition species provide a protective film upon the previously etched surface to protect the surface, typically the sidewalls of the trench, from further etching. These two steps are repeated as a deeper and deeper trench is formed. Poor control of the cyclical etch process disadvantageously increases the roughness of the sidewalls, which may render a microelectronic device defective.
Further, deposition of the deposition species is not well controlled and can result in the deposition species being deposited on a surface to be etched. Accordingly, either an additional process step must be included to remove the deposition species from the surface to be etched, or an etch step must proceed for a longer duration to first remove the deposition species to reach the surface to be etched. Therefore, poor control of the deposition species can result in a longer duration for the cyclical etch process.
Therefore, improved methods for etching a substrate are provided herein.